The data collected thus far indicates that the majority of 9-banded armdillos will develop disseminated leprosy following inoculation with M. leprae. In earlier studies, 45% of the animals inoculated developed the disease while in later studies using a uniform source of inoculum and younger and presumably immunologically less capable animals, 62% developed this disease. Immunologic studies have shown that the majority of normal, healthy armadillos are lepromin negative while all of the animals tested with PPD were negative . In vitro immunologic testing suggests an immune deficiency that is temperature related. With the large amounts of infected tissue now available, many avenues of investigation are now open. In addition, studies concerned with the immunology of an animal species naturally susceptible to leprosy are now possible.